Ink jet recording method

ABSTRACT

An ink jet recording method for recording an image on a recording medium using a first liquid A for forming the image containing a polymerizable or crosslinkable material, and a second liquid B having a different composition from the composition of the first liquid A, the method including: applying the second liquid B, having a solubility parameter value of 35 or less and a difference of the solubility parameter value of 10 or less from the solubility parameter value of the first liquid A, onto the same area at which the image is to be formed by the first liquid A or a wider area than the area at which the image is to be formed by the first liquid A, of the recording medium which is impermeable or slowly-permeable; and jetting the first liquid A onto the recording medium where the second liquid B has been applied so that at least a droplet a 1  and a droplet a 2  of the first liquid A have an overlap portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35USC 119 from Japanese PatentApplication No.2005-289362, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink jet recording method,particularly to an ink jet recording method suitable for forming a highquality image at high speed by curing using a plurality of liquids.

2. Description of the Related Art

An ink jet system that ejects ink from an ink jetting port such as anozzle is used in many printers for the reason that it is small-sizedand inexpensive and it can form an image without contact between the inkjet system and a printing medium. Among these ink jet systems, a piezoink jet system that utilizes the deformation of a piezo element to jetink and a thermal ink jet system that utilizes a boiling phenomenon ofink which is caused by thermal energy have high resolution andhigh-speed printing ability.

Currently, it is important tasks to attain high-speed printing and highimage quality when the ink is jetten on a plain paper or non-waterabsorbing recording media such as plastic.

In ink jet recording, ink (liquid) droplets are continuously ejected asdroplet n1, droplet n2, droplet n3, . . . , and droplet nx, to form aline or an image composed of the droplet n1, droplet n2, droplet n3, . .. , and droplet nx on a recording medium. However, ink jet recording hassome practical problems; if drying of the jetted droplets takes a longtime, the formed image tends to blur, and the adjacent ink droplets n1and n2 may be mixed to hinder the formation of a sharp image.Furthermore, when a non-water absorbing recording medium is used, dryingof ink solvents is so slow that the recorded sheets cannot be stackedimmediately after printing until the solvents dry. If droplets aremixed, adjacently jetted droplets may coalesce to migrate from the pointof deposition. This causes uneven line width in forming a thin line, andcolor unevenness in forming a colored surface.

One of the method for preventing printing problems such as imageblurring and uneven line width is the acceleration of ink curing. Forexample, a technique of curing and fixing of ink not by evaporating theink solvent but by irradiation has been supposed. More specifically, atwo-liquid type ink, which achieves both the storage stability and rapiddrying property of an image, is used, and the two liquids react witheach other on a recording medium. For example, a method of jetting anink containing an anionic dye after applying a liquid containing a basicpolymer as described in Japanese Patent Application Laid-Open (JP-A) No.63-60783, a method of applying an ink containing an anionic compound anda coloring material after applying a liquid composition containing acationic substance as described in JP-A No. 8-174997, and a recordingmethod using an ink containing a light-curable resin and aphotopolymerization initiator as described in U.S. Pat. No. 3,478,495are disclosed.

Although these methods can prevent image blurring to some degree, theyare not sufficient for preventing uneven line width, color unevenness orother problems caused by mixing of ink droplets. Furthermore, aqueoussolvents used in these methods dry slowly, and jetted dyes tend to beunevenly distributed, and then the image quality may deteriorate.

As a technique with regard to the above-described problems, a method ofcuring and fixing an ink, which contains a pigment as the coloringcomponent, by irradiation is described in JP-A No. 8-218018. In themethod, a pixel is formed using either an ink containing a solidifyingmonomer or an ink containing a pigment dispersion, subsequently anotherpixel is formed using the remaining ink at the same point with theabove-described image, and the inks are cured with ultraviolet light,electron beam or the like.

Furthermore, in a method as described in JP-A No. 2001-348519, an inkcomposition containing water, a reactive monomer, a colorant, and othercomponents and an aggregating solution containing a coagulant causingcoagulation are used, wherein the above-described coagulating solutionis applied to a recording medium, and thereon the above-described inkcomposition is applied. Furthermore, a method of applying an inkcomposition containing a monomer after applying a reaction liquidcontaining a photopolymerization initiator all over the surface, andcuring by ultraviolet radiation is described in U.S. Pat. No. 3,642,152.

In addition to the above-described methods, a method of overlappedlyjetting two separate inks is described in JP-A No. 2000-135781.

SUMMARY OF THE INVENTION

The first embodiment of the present invention is an ink jet recordingmethod for recording an image on a recording medium using a first liquidA for forming the image containing a polymerizable or crosslinkablematerial, and a second liquid B having a different composition from thecomposition of the first liquid A, the method comprising:

applying the second liquid B, having a solubility parameter value of 35or less and a difference of the solubility parameter value of 10 or lessfrom the solubility parameter value of the first liquid A, onto the samearea at which the image is to be formed by the first liquid A or a widerarea than the area at which the image is to be formed by the firstliquid A, of the recording medium which is impermeable orslowly-permeable; and

jetting the first liquid A onto the recording medium where the secondliquid B has been applied so that at least a droplet a1 and a droplet a2of the first liquid A have an overlap portion.

DETAILED DESCRIPTION OF THE INVENTION

The ink jet recording method of the present invention forms a desiredimage by ejecting the first droplet a1, droplet a2, . . . , and dropletax, which are derived from the first liquid A, from an ink ejecting port(head) of an ink jet printer to an impermeable or slowly-permeablerecording medium. In order to form a desired image, the first liquid Acomprises at least a polymerizable or crosslinkable material, and inorder to achieve a high image density, the first droplet a1 and dropleta2 are jetted in such a manner they are overlapped each other. Beforeapplying the above-described droplet a1 and droplet a2, the secondliquid B having a composition different from that of the above-describedliquid A is applied to the same area with or a wider area than theabove-described desired image area onto the above-described recordingmedium. The above-described liquid B has a solubility parameter value of35 or less, and the difference of the solubility parameter value betweenthe above-described liquid A and liquid B is 10 or less. Herein, thesolubility parameter value refers to “sp value”.

In the ink jet recording method of the present invention, an impermeableor slowly-permeable recording medium is used as the recording medium. Inimage recording on such a recording medium with low liquid absorbency,if adjacent droplets (the first droplet a1 and droplet a2), which hadbeen overlappedly applied to achieve a high image density, are incontact each other on the medium before drying, they tend to coalesceeach other to cause image blurring or uneven line width of a thin line,resultingly the formability of a sharp image can be impaired. However,when the liquid B having the specified sp value is jetted before jettingthe first droplet a1 and droplet a2, coalescence of the overlappedlyapplied droplet a1 and droplet a2 is inhibited, and problems such asimage blurring and uneven line width of a thin line in an image areeffectively prevented. Accordingly, a sharp line having a uniform widthcan be formed with keeping an image resolution of high image density,thereby a high quality image can be recorded. Furthermore, the image haslow stickiness and excellent rubbing resistance.

The impermeable recording medium refers to a medium which issubstantially impermeable to droplets. “Substantially impermeable” meansthat the permeation rate measured one minutes after ink deposition is 5%or less. The slowly-permeable recording medium refers to a medium onwhich the complete permeation of 10 pl (picoliter) of droplets takes 100mseconds or more, and specific examples thereof include art paper. Thedetail of the impermeable or slowly-permeable recording medium will bedescribed later.

Permeable recording medium refers to a medium on which the completepermeation of 10 pl of droplets takes 100 m seconds or less, andspecific examples thereof include plain paper and porous paper.

The first droplet a1 is jetted onto the above-described recordingmedium, and then the subsequent first droplet a2 is jetted in such amanner it overlaps the above-described droplet a1. Before applying thefirst droplet a1 and droplet a2, the second liquid B having acomposition different from that of the first liquid A is applied to thesame area with or a wider area than the image area to be formed by theabove-described droplet a1 and droplet a2 onto the recording medium.

In the present invention, as the liquids for forming an image, the firstliquid A containing the first droplet a1 and droplet a2, and the secondliquid B having a composition different from that of the first liquid Aare used. The first droplet a1 and droplet a2 refer to the dropletsamong the droplets a1, a2, a3, . . . , and ax of a single first liquidA, which are ejected from an ink ejecting port and overlappedly jetted.The droplets may be simultaneously jetted droplets, or sequentiallyjetted preceding and subsequent droplets, and are preferablysequentially jetted preceding and subsequent droplets. The first liquidA and the second liquid B have different compositions.

In the present invention, the sp value of the second liquid B, which isapplied before applying the first liquid A, is 35 or less, and thedifference of the sp value between the first liquid A and the secondliquid B is 10 or less.

When the sp value is 35 or less, the second liquid B has higher affinityto, for example as described later, the first liquid A (droplet a1,droplet a2, . . . ) containing a polymerizable or crosslinkablematerial. Accordingly, coalescence between the overlappedly appliedfirst droplet a1 and droplet a2 is inhibited, thereby image blurring anduneven line width of a thin line in an image can be effectivelyprevented.

In the second liquid B, the above-described sp value is more preferably30 or less, and most preferably 25 or less. The difference of the spvalue between the first liquid A and the second liquid B is morepreferably 5 or less.

Furthermore, when the difference of the sp value between the firstliquid A and the second liquid B is within the above-described range,the liquids are readily soluble in each other. The contact area betweenthe droplet a1 and droplet B is larger than that between the droplet a1and droplet a2, thus the droplet a1 is more compatible with the secondliquid B. Accordingly, for example, when the overlappedly applieddroplet a1, droplet a2, . . . droplet ax contain colorants, colorblurring or mixing between the droplet a1 and droplet a2, and unevenline width of a colored line image are effectively prevented.

The sp value is determined for various solvents and solutes, and showsthe affinity between solvents or between a solvent and a solute. Whentwo solvents are compatible each other, the sp value is calculated fromthe energy change at the time when a solute is dissolved in a solvent.The sp value used in the present invention has been calculated,specifically, using the sp value calculation program by R. L. Smith atTohoku University. The calculation is carried out on the basis of atemperature of 25° C., wherein compounds containing no carbon atom areexcluded, constitutional units such as polymer and polyethylene chainsare treated as saturated repeating units having dangling bonds (e.g.,styrene is —CH₂—CH(C₆H₅)—), and water (H₂O) is calculated as 47.8.

In the ink jet recording method of the present invention, theaforementioned first droplet a1 and droplet a2 are jetted using an inkjet nozzle or the like. The second liquid B is applied not only byejection using an ink jet nozzle, but also by other means such asapplication.

The means for applying the second liquid B to the recording medium isdescribed. The means for jetting the first droplet a1 and droplet a2(the first liquid A) is described mainly focusing on ejection the abovedescribed ink jet nozzle. Specific examples will be described.

(i) Application with coater

It is a preferable embodiment that the second liquid B is applied to arecording medium using a coater, subsequently the droplets a1 and a2(the first liquid A) are jetted by an ink jet nozzle to record an image.

The coater is not particularly limited, and can be appropriatelyselected from known coaters according to the intended use. Examples ofthe coater include an air doctor coater, a blade coater, a rod coater, aknife coater, a squeeze coater, an impregnation coater, a reverse rollcoater, a transfer roll coater, a gravure coater, a kiss-roll coater, acast coater, a spray coater, a curtain coater, and an extrusion coater.Details of the method may be referenced in “Coating Kogaku (CoatingEngineering)”, by Yuji Harasaki.

The ink jet nozzle is not particularly limited, and can be appropriatelyselected from known nozzles according to the intended use. The ink jetrecording method will be described later.

Furthermore, liquids other than the first droplet a1, droplet a2 (thefirst liquid A), and the second liquid B may be used. The other liquidsmay be applied to a recording medium by any methods such as theabove-described coating using coaters or ejection using an ink jetnozzle. The timing of application is not particularly limited. Liquidscontaining a colorant is preferably injected using an ink jet nozzle,and preferably applied after applying the second liquid B.

(ii) Ejection ink with ink jet nozzle

It is a preferred embodiment to record an image by injecting the secondliquid B as droplet b1, droplet b2, droplet b3, . . . , and droplet bxusing an ink jet nozzle, followed by jetting the first droplet a1,droplet a2, droplet a3, . . . , and droplet ax (the first liquid A)using an ink jet nozzle. The ink jet nozzle is the same as describedabove.

Also in this instance, the liquids other than the first droplet a1,droplet a2 (the first liquid A), and the second liquid B may be appliedto a recording medium by any methods such as coating using a coater orejection using an ink jet nozzle, and the timing of application is notparticularly limited. Liquids containing a colorant is preferablyinjected using an ink jet nozzle, and preferably applied after applyingthe second liquid B.

The methods for ejecting with an ink jet nozzle (ink jet recordingmethods) will be described below.

In the present invention, preferable examples include known methods suchas a charge control method which uses electrostatic attraction to ejectink, a drop-on-demand method (pressure pulse method) which usesvibration pressure of a piezo element, an acoustic ink jet method inwhich an electric signal is transformed into an acoustic beam and ink isirradiated with the acoustic beam so as to be ejected by radiationpressure, and a thermal ink jet (bubble jet (Registered trademark))method which uses pressure caused by bubbles formed by heating ink.

Examples of the ink jet recording method include a method which uses inkhaving low concentration called photo ink to eject a multitude of inkdroplets having a small volume, a method which uses a plurality of inkshaving substantially the same color hue but different concentrations toimprove image quality, and a method which uses colorless transparentink.

In instances where the above-described application means (i) is used, atleast the first droplet a1 and second droplet a2 are jetted by the inkjet recording method on the second liquid B which has been applied tothe recording medium in advance, thereby an image is formed. Ininstances where the above-described application means (ii) is used, atleast the first droplet a1 and the first droplet a2 are jetted by theink jet recording method on the second liquid B which has been appliedto the recording medium by the ink jet recording method in advance,thereby an image is formed.

In the present invention, the droplet a1 and droplet a2 has a overlapportion, which increases the number of jetted droplets per unit length,and thereby allows image recording at a high resolution. In thisinstance, it is preferable to deposit the first droplet a1 and dropleta2 within 1 second after applying the second liquid B to a recordingmedium.

The overlap ratio of droplets at an overlap portion refers to a valuemeasured at the time of 1 second after at least the droplet a1 anddroplet a2 are overlappedly jetted. In particular, the overlap ratio ispreferably 10% to 90%, since it is effective for image recording withhigher resolution.

Furthermore, the overlap ratio is more preferably 20% to 80%, andfurthermore preferably 30% to 70%.

The above-described overlap ratio is an index showing the ratio ofoverlapping between adjacent droplets (droplet a1, droplet a2, . . . ).When the diameter of a droplet jetted on a recording medium is set at aand the portion of ½a is overlapped, the overlap ratio is 50%. In thepresent invention, adjacently jetted droplets can keep the jetted shapewithout causing coalescence, and the overlap ratio is represented by100×(2b-c)/2b [%], wherein b is the radius of the droplet measured atpoint in time of 1 second after deposition, and c is the distanceinterval of the adjacently jetted droplets (distance between the centersof the adjacent droplets).

The amount of deposition of the first droplet a1 and the first dropleta2 is not particularly limited, and can be selected in accordance withthe sharpness of the image to be recorded. Usually, the amount ispreferably about 0.5 pl to 10 pl per droplet. Furthermore, applicationof the second liquid B is not particularly limited as long as it isapplied to the same area with or a wider area than the image area formedby the first droplet a1 and droplet a2.

Concerning the proportion of the applied amount of the second liquid Bper one droplet of the first droplet a1 or the first droplet a2, whenthe amount of the droplet a1 or droplet a2 is 1, the amount ofapplication of the second liquid B (mass ratio) is preferably in therange of 0.05 to 5, more preferably in the range of 0.07 to 1, and mostpreferably in the range of 0.1 to 1.

The first droplet a1 and/or droplet a2 is preferably jetted at a dropletsize (volume) of 0.1 pL (picoliter; hereinafter the same shall apply) to100 pL (preferably from an ink jet nozzle). When the droplet size iswithin the above-described range, an image with high sharpness can beformed at a high density. Furthermore, the size is more preferably 0.5pL to 50 pL.

A time interval between the finishing point of the application of thesecond liquid B and the starting point of the jetting of each droplet ofthe first liquid A is in the range of 5 μ seconds to 400 m seconds. Whenthe time interval is within the above-described range, the effect of thepresent invention is advantageously achieved. The time interval is morepreferably 10 μ seconds to 300 m seconds, and most preferably 20 μseconds to 200 μ seconds.

The physical properties of the first liquid (droplet) and second liquid(droplet) jetted on a recording medium by the ink jet recording methodare different depending on apparatuses. In usual cases, the viscosity ofthem at 25° C. is preferably in the range of 5 to 100 mPa·s, and morepreferably in the range of 10 to 80 mPa·s. The surface tension ispreferably in the range of 20 to 60 mN/m, and more preferably in therange of 30 to 50 mN/m. In the relationship between the first liquid Aand the second liquid B, the difference in viscosity (25° C.) ispreferably 25 mPa·s or lower, and the difference in surface tension ispreferably 20 mN/m or lower.

In the present invention, after jetting the first droplet a1 and dropleta2 after applying the second liquid B as described above, and thenenergy may be applied to fix the recorded image from the viewpoint ofachieving excellent fixing properties. The application of energypromotes the curing reaction due to polymerization or crosslinking ofthe polymerizable or crosslinkable material contained in the liquids,thereby a more solid image is more effectively formed. For example, in asystem containing a polymerization initiator, the application of activeenergy such as activation light and heat promotes the generation ofactive species due to the decomposition of the polymerization initiator,and the increased active species and temperature promote the curingreaction of the polymerizable or crosslinkable material due topolymerization or crosslinking caused by the active species.

The application of energy can be appropriately carried out by activationlight irradiation or heating.

As the above-described activation light, for example, ultraviolet light,visible light, as well as α ray, γ ray, X ray, and electron beam or thelike may be used. Among them, ultraviolet light and visible light arepreferable, and ultraviolet light is most preferable from the viewpointsof cost and safety.

While the amount of energy necessary for curing reaction is differentdepending on the kind and content of the polymerization initiator, it isusually about 1 to 500 mJ/cm².

When energy is applied by heating, the heating treatment is preferablycarried out for 0.1 to 1 second under conditions that the surfacetemperature of the recording medium is in the range of 40 to 80° C.

The heating treatment can be carried out by a non-contact type heatingmethod. Preferable examples of the heating method include a heatingmethod of passing through a heating furnace such as an oven, and aheating method by whole surface exposure with ultraviolet light tovisible light to infrared light or the like. Examples of the lightsource suitable for exposure as a heating method include a metal halidelamp, a xenon lamp, a tungsten lamp, a carbon arc lamp, and a mercurylamp.

—Recording medium—

As the recording medium, an impermeable or slowly-permeable recordingmedium is used.

Examples of the impermeable recording medium include synthetic resins,rubber, resin coated paper, glass, metal, ceramic, and wood.Furthermore, these materials may be used in combination of two or moreas composite substrates for the purpose of adding functions.

As the above-described synthetic resin, any synthesis resins may beused. Examples thereof include polyester such as polyethyleneterephthalate, and polybutadiene terephthalate, polyolefin such aspolyvinyl chloride, polystyrene, polyethylene, polyurethane, andpolypropylene, acrylic resin, polycarbonate,acrylonitrile-butadiene-styrene copolymer, diacetate, triacetate,polyimide, cellophane, and celluloid. The thickness and shape of thesesynthesis resins are not particularly limited, and the shape may beeither film, card, or block form. Furthermore, the resins may be eithertransparent or opaque.

The above-described synthesis resin is preferably used in film formwhich is suitable for so-called soft packaging, and examples thereofinclude various non-absorbing plastics and films thereof. Examples ofthe plastic film include a PET film, an OPS film, an OPP film, a PNyfilm, a PVC film, a PE film, and a TAC film. Other examples of theplastics include polycarbonate, acrylic resin, ABS, polyacetal, PVA, andrubbers.

Examples of the above-described resin coated paper include a transparentpolyester film, an opaque polyester film, an opaque polyolefin resinfilm, and a paper support laminated with a polyolefin resin on bothsides. Among them, a paper support laminated with a polyolefin resin onboth side surfaces is most preferable.

The above-described metal is not particularly limited, and preferableexamples thereof include aluminum, iron, gold, silver, copper, nickel,titanium, chromium, molybdenum, silicon, lead, zinc, stainless steel,and composite materials thereof.

Furthermore, read-only optical disks such as CD-ROM and DVD-ROM,write-once optical disks such as CD-R and DVD-R, and re-writable opticaldisks can be used, and an ink receiving layer and a brightening layermay be added to the label surface.

The first liquid A (droplets a1, a2, . . . ) and the second liquid Bused in the ink jet recording method of the present invention, and thevarious constituents thereof are further described in detail.

—First liquid A (droplet ax including the first droplet a1 and dropleta2)—

The first liquid A (droplet ax including the first droplet a1 anddroplet a2) according to the present invention is jetted on thebelow-mentioned second liquid B which has been previously applied to therecording medium to constitute a recorded image, comprises at least apolymerizable or crosslinkable material, and preferably comprises acolorant and a lipophilic solvent. As necessary, the liquid may furthercomprise a polymerization initiator or other components.

<Polymerizable or Crosslinkable Material>

The first liquid A (droplet ax including the first droplet a1 anddroplet a2) contains at least one kind of polymerizable or crosslinkablematerial. The polymerizable or crosslinkable material has functions ofcausing polymerization or crosslinking reaction by an initiating speciessuch as a radical generated from the below-mentioned polymerizationinitiator or the like, and curing.

As the polymerizable or crosslinkable material, known polymerizable orcrosslinkable materials such as those causing radical polymerizationreaction, cation polymerization reaction, or dimerization reaction(hereinafter collectively referred to as polymerizable material) can beused. Examples thereof include addition polymerizable compounds havingat least one ethylene-based unsaturated double bond, epoxy-basedcompounds, oxetane-based compounds, oxirane-based compounds, polymercompounds having a maleimide in the side chain, and polymer compoundshaving a cinnamyl group, a cinnamylidene group, or a chalcone group,which has an unsaturated double bond capable of photodimerizationadjacent to an aromatic nuclear, in the side chain. Among them, additionpolymerizable compounds having at least one ethylene-based unsaturateddouble bond are more preferable, and those selected from the compounds(monofunctional or multifunctional compounds) having at least one, morepreferably two or more terminal ethylene-based unsaturated bonds aremost preferable. Specifically, the material can be selected from thecompounds widely known in the industrial field of the present invention,and examples thereof include those having a chemical form of monomers,prepolymers or dimers, trimers, and oligomers, mixtures thereof, andcopolymers thereof.

Specifically, preferable examples of the polymerizable or crosslinkablematerial include compounds having a polymerizable group such as anacryloyl group, a methacryloyl group, an allyl group, a vinyl group, andan internal double bond group (e.g. , maleic acid) within the molecule,and among them, compounds having acryloyl groups or methacryloyl groupsare preferable from the viewpoint of causing curing reaction at lowenergy.

Examples of the above-described multifunctional compound include vinylgroup-containing aromatic compounds, (meth)acrylates which are esters ofa bivalent or higher valent alcohol and (meth)acrylic acid,(meth)acrylamides which are amides of a bivalent or higher valent amineand (meth)acrylic acid, polyester (meth)acrylate in which (meth)acrylicacid is introduced into an ester obtained by combining a polybasic acidwith a bivalent alcohol or polycaprolactone, polyether (meth)acrylate inwhich (meth)acrylic acid is introduced into an ether obtained bycombining an alkylene oxide with a polyvalent alcohol, epoxy(meth)acrylate obtained by introducing (meth)acrylic acid into an epoxyresin, or by reacting a bivalent or higher valent alcohol with aepoxy-containing monomer, urethane acrylates having urethane bonds,amino resin acrylates, acrylic resin acrylates, alkyd resin acrylates,spiran resin acrylates, silicone resin acrylates, reaction products ofan unsaturated polyester and the above-described photopolymerizablemonomer, and reaction products of a wax and the above-describedpolymerizable monomer.

Among them, (meth)acrylate, polyester (meth)acrylate, polyether(meth)acrylate, epoxy acrylate, urethane acrylate, acrylic resinacrylate, silicone resin acrylate, and reaction products of anunsaturated polyester and the above-described photopolymerizable monomerare preferable. Acrylate, polyester acrylate, polyether acrylate, epoxyacrylate, and urethane acrylate are most preferable.

In the present description, (meth)acrylic acid refers to both acrylicacid and methacrylic acid.

Specific examples of the above-described multifunctional compoundinclude divinylbenzene, 1,3-butanediol diacrylate, 1,6-hexanedioldiacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate,dipentaerythritol hexaacrylate, 1,6-acryloyl aminohexane, hydroxypivalic acid ester neopentyl glycol diacrylate, polyester acrylatehaving (meth)acryloyl groups at the ends of the molecular chain ofpolyester composed which is produced by a dibasic acid and a divalentalcohol has a molecular weight of 500 to 30000, polyethyleneglycoldiacrylate, epoxy acrylates having a bisphenol (A, S, or F) skeleton anda molecular weight of 450 to 30000, epoxy acrylates containing a phenolnovolac resin skeleton and having a molecular weight of 600 to 30000,reactants of a polyvalent isocyanate and a (meth)acrylic acid monomerhaving hydroxy groups, and having a molecular weight of 350 to 30000,and urethane modified products having urethane bonds within themolecule.

Examples of the monofunctional compound include (meth)acrylate, styrene,acrylamide, vinyl group-containing monomers (e.g. , vinyl esters, vinylethers, and N-vinyl amides), and (meth)acrylic acid. Among them,(meth)acrylate, acrylamide, vinyl esters, and vinyl ethers arepreferable, and (meth)acrylate and acrylamide are most preferable.

The polymerizable compound may be nonsubstituted or substituted.Examples of the possible substituent include a halogen atom, a hydroxygroup, an amide group, and a carboxylic acid group.

Specific examples of the above-described monofunctional compound includehydroxyethyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate,dicyclopentenyl acrylate, 2-acryloyloxyethyl phosphate, allyl acrylate,N,N-dimethylaminoethyl acrylate, N,N-dimethyl acrylamide, N,N-diethylaminopropyl acrylamide, N-butoxymethyl acrylamide, acryloyl morpholine,2-hydroxyethylvinyl ether, N-vinyl formamide, N-vinyl acetamide,2-cyclohexyl carbamoyloxyethyl acrylate, acrylates having a polybutylacrylate moiety in an ester, and acrylates having a polydimethylsiloxane moiety in an ester.

The polymerizable or crosslinkable material may be used alone or incombination of two or more thereof.

The content of the polymerizable or crosslinkable material in the firstliquid or, as necessary, in the second liquid is, preferably in therange of 50 to 99.6% by mass, more preferably in the range of 70 to99.0% by mass, and further preferably in the range of 80 to 99.0% bymass based on the total solid (mass) of the droplets.

The content of the polymerizable or crosslinkable material in thedroplets is preferably in the range of 20 to 98% by mass, morepreferably in the range of 40 to 95% by mass, and most preferably in therange of 50 to 90% by mass based on the total weight or the droplets.

The first liquid A (droplet ax including the first droplet a1 anddroplet a2) is prepared in such a manner that the difference of the spvalue between the first liquid A and the second liquid B is 10 or less.When the difference of the sp value between the first droplet a1 and thesecond liquid B, which is applied before jetting the first droplet a1,is 10 or less, they have high affinity to each other, and thecoalescence between the first droplet a1 and the subsequent droplet a2,which is jetted in contact with the first droplet a1, is effectivelyprevented. The sp value can be appropriately adjusted using abelow-mentioned lipophilic solvent, a polymerizable material or thelike. For example, the sp value can be reduced by increasing theproportion of a lipophilic solvent in the droplets.

Details and preferable embodiments of the colorant, lipophilic solvent,polymerization initiator, and other components which can be contained inthe first liquid A (droplet ax including the first droplet a1 anddroplet a2) will be described later.

—Second liquid B—

In the present invention, before jetting the aforementioned firstdroplet a1, the second liquid B, which has a composition different fromthat of the first droplet a1, droplet a2, . . . (the first liquid A), isapplied to the recording medium in the same area with or a wider areathan the image area formed onto the recording medium by at least thefirst droplet a1 and droplet a2.

The second liquid B has been prepared in such a manner it has a sp valueof 35 or less. The second liquid B is water-insoluble, and adjusted tohave properties of an oil-soluble organic solvent. At least theaforementioned first droplet a1 contains a polymerizable orcrosslinkable material and can be appropriately prepared as an organicsolvent. When the droplet is prepared as an organic solvent, it isreadily mixed with the second liquid B, therefore coalescence betweenthe first droplet a1 and droplet a2, which are overlappedly jetted incontact with each other, is effectively avoided. Accordingly, asaforementioned, image blurring and uneven line width of a thin line inan image are effectively prevented.

The sp value of the second liquid B can be appropriately adjusted usinga lipophilic solvent or the like. In a preferable embodiment of theadjustment, the content of the lipophilic solvent is in the range of 50%by mass to 100% by mass based on the total weight of the second liquidB. When the content of the lipophilic solvent is within theabove-described range, the sp value can be reduced to 35 or less. The spvalue is preferably in the range of 30 or less.

<Lipophilic Solvent>

The lipophilic solvent is effective for preventing image blurring anduneven line width of a thin line in an image, and is capable ofadjusting the sp value of the second liquid within the aforementionedrange.

“Lipophilic” compounds refer to those having a solubility of 1 g or lessin 100 cc of water.

The lipophilic solvent may be contained in the second liquid B and/orthe aforementioned first liquid A. Alternatively, it may be contained ina liquid other than the second liquid B and the first liquid A.

Examples of the lipophilic solvent include high-boiling point organicsolvents and above-described polymerizable materials, and is preferablya high-boiling point organic solvent.

Preferable high-boiling point organic solvents in the present inventionare mainly described below.

The above-described high-boiling point organic solvent preferably has(1) a viscosity of 100 mPa·s or less at 25° C. or 30 mPa·s or less at60° C., and (2) a boiling point higher than 100° C.

High-boiling point organic solvents which do not satisfy either of theviscosity conditions as described in above (1) are so viscous that theycan hinder the application to a recording medium, and high-boiling pointorganic solvents which do not satisfy either of the viscosity conditionsas described in above (2) can evaporate during image forming becausethey have a too low boiling point, which may result in the impairment ofthe effect of the present invention.

For the conditions as described in above (1), the viscosity at 25° C. ismore preferably in the range of 70 mPa·s or lower, more preferably, inthe range of 40 mPa·s or lower, and most preferably in the range of 20mPa·s or lower. The viscosity at 60° C. is more preferably in the rangeof 20 mPa·s or lower, and most preferably in the range of 10 mPa·s orlower. For the conditions as described in above (2), the boiling pointis more preferably in the range of 150° C. or higher, and mostpreferably in the range of 170° C. or higher. The lower limit of themelting point is preferably in the range of 80° C. or lower.Furthermore, the solubility of water (25° C.) is preferably 4 g or less,more preferably in the range of 3 g or less, further preferably in therange of 2 g or less, and most preferably in the range of 1 g or less.

The above-described “viscosity” has been determined using a RE80 typeviscometer (manufactured by Toki Sangyo Co., Ltd.). The RE80 typeviscometer is a conical-frustum type viscometer corresponding to an Etype. The viscosity was measured at a rotational speed of 10 r.p.m.using a rotor of rotor code No.1. The rotational speed was as necessarychanged to 5 r.p.m., 2.5 r.p.m., 1 r.p.m., 0.5 r. p.m., or others formeasuring solvents having a viscosity higher than 60 mPa·s. “Solubilityof water” refers to the saturation density of water in a high-boilingpoint organic solvent at 25° C., and means the mass (g) of water solublein 100 g of the high-boiling point organic solvent at 25° C.

As the above-described high-boiling point organic solvent, the compoundsrepresented by the following formulae [S-1] to [S-9] are preferable.

In the above-described formula [S-1], R₁, R₂ and R₃ each independentlyrepresent an aliphatic group or an aryl group. a, b, and c eachindependently represent 0 or 1.

In the formula [S-2], R₄ and R₅ each independently represent analiphatic group or an aryl group, R₆ represents a halogen atom (F, Cl,Br, I, hereinafter the same), an alkyl group, an alkoxy group, anaryloxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group, andd represents an integral number of 0 to 3. When d is two or more, aplurality of R₆s may be the same or different from each other.

In the formula [S-3], Ar represents an aryl group, e represents anintegral number of 1 to 6, and R₇ represents a hydrocarbon group havinga valence of e or hydrocarbon groups linked each other by an ether bond.

In the formula [S-4], R₈ represents an aliphatic group, f represents anintegral number of 1 to 6, and R₉ a hydrocarbon group having a valenceof f or hydrocarbon groups linked each other by an ether bond.

In the formula [S-5], g represents an integral number of 2 to 6, R₁₀represents a hydrocarbon group having a valence of g (excluding an arylgroup), and R₁₁ represents an aliphatic group or an aryl group.

In the formula [S-6], R₁₂, R₁₃ and R₁₄ each independently representhydrogen atom, an aliphatic group, or an aryl group. X represents —CO—or —SO₂—. R₁₂ and R₁₃ or R₁₃ and R₁₄ may be linked each other to form aring.

In the formula [S-7], R₁₅ represents an aliphatic group, analkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group,an arylsulfonyl group, an aryl group or a cyano group, R₁₆ represents ahalogen atom, an aliphatic group, an aryl group, an alkoxy group or anaryloxy group, h represents an integral number of 0 to 3. When h is twoor more, a plurality of R₁₆s may be the same or different.

In the formula [S-8], R₁₇ and R₁₈ each independently represent analiphatic group or an aryl group, R₁₉ represents a halogen atom, analiphatic group, an aryl group, an alkoxy group, or an aryloxy group, irepresents an integral number of 0 to 5. When i is two or more, aplurality of R₁₉s may be the same or different from.

In the formula [S-9], R₂₀ and R₂₁ each independently represent analiphatic group or an aryl group. j represents 1 or 2. R₂₀ and R₂₁ maybe linked each other to form a ring.

In the formulae [S-1] to [S-9], when R₁ to R₆, R_(8, R) ₁₁ to R₂₁ aregroup containing an aliphatic group or an aliphatic group, the aliphaticgroup may be straight-chain, branched-chain, or cyclic, and may containunsaturated bonds or have substituents. Examples of the substituentinclude a halogen atom, an aryl group, an alkoxy group, an aryloxygroup, an alkoxycarbonyl group, a hydroxy group, an acyloxy group, andan epoxy group.

In the formulae [S-1] to [S-9], when R₁ to R₆, R₈, R_(11 to R) ₂₁ arecyclic aliphatic groups, namely cycloalkyl groups or groups containing acycloalkyl group, the cycloalkyl group may contain unsaturated bondswithin a 3- to 8-membered ring, and may have substituents orcrosslinking groups. Examples of the substituent include a halogen atom,an aliphatic group, a hydroxy group, an acyl group, an aryl group, analkoxy group, and an epoxy group, and examples of the crosslinking groupinclude methylene, ethylene, and isopropylidene.

In the formulae [S-1] to [S-9], when R₁ to R₆, R₈, R₁₁ to R₂₁ Ar, arearyl groups or groups containing an aryl group, the aryl group may besubstituted with a substituent such as a halogen atom, an aliphaticgroup, an aryl group, an alkoxy group, an aryloxy group, andalkoxycarbonyl group.

In the formulae [S-3], [S-4], and [S-5], when R₇, R₉ or R₁₀ is ahydrocarbon group, the hydrocarbon group may contain a cyclic structure(e.g. , a benzene ring, a cyclopentane ring, a cyclohexane ring) or anunsaturated bond, and may have substituents. Examples of the substituentinclude a halogen atom, a hydroxy group, an acyloxy group, an arylgroup, an alkoxy group, an aryloxy group, and epoxy group.

Among the high-boiling point organic solvents represented by theformulae [S-1] to [S-9], the most preferable high-boiling point organicsolvents are further described below.

In the formula [S-1], R₁, R₂, and R₃ are each independently preferablyan aliphatic group having 1 to 24 (preferably 4 to 18) carbon atoms(e.g., n-butyl, n-hexyl, n-octyl, EH-octyl, 2-ethylhexyl,3,3,5-trimethylhexyl, 3,5,5-trimethylhexyl, n-dodecyl, n-octadecyl,benzyl, oleyl, 2-chloroethyl, 2,3-dichloropropyl, 2-butoxyethyl,2-phenoxyethyl, cyclopentyl, cyclohexyl, 4-t-butylcyclohexyl, and4-methylcyclohexyl), or an aryl group having 6 to 24 (preferably 6 to18) carbon atoms (e.g., phenyl, cresyl, p-nonyl phenyl, xylyl, cumenyl,p-methoxyphenyl, and p-methoxycarbonylphenyl). Among them, R₁, R₂, andR₃ are most preferably n-hexyl, n-octyl, EH-octyl, 2-ethylhexyl,3,5,5-trimethylhexyl, n-dodecyl, 2-chloroethyl, 2-butoxyethyl,cyclohexyl, phenyl, cresyl, p-nonyl phenyl, or cumenyl.

Each of a, b, and c represents 0 or 1, and more preferably all of a, b,and c are 1.

In the formula [S-2], R₄ and R₅ are each independently preferably analiphatic group having 1 to 24 (preferably 4 to 18) carbon atoms (e.g.,the aliphatic groups as listed for the above-described R₁, heptyl,ethoxycarbonylmethyl, 1,1 -diethylpropyl, 2-ethyl-1-methylhexyl,cyclohexylmethyl, 1-ethyl-1,5-dimethylhexyl, 3,5,5-trimethylcyclohexyl,menthyl, bomyl, 1-methylcyclohexyl), or an aryl group having 6 to 24(preferably 6 to 18) carbon atoms (e.g., the aryl groups as listed forthe above-described R₁, 4-t-butylphenyl, 4-t-octylphenyl,1,3,5-trimethylphenyl, 2,4,-di-t-butylphenyl, and 2,4,-di-t-pentylphenyl). Among them, R₄ and R₅ are more preferably an aliphatic group,and most preferably n-butyl, heptyl, 2-ethylhexyl, n-dodecyl,2-butoxyethyl, or ethoxycarbonylmethyl.

R₆ is preferably a halogen atom (preferably, a chlorine atom), an alkylgroup having 1 to 18 carbon atoms (e.g., methyl, isopropyl, t-butyl, andn-dodecyl), an alkoxy group having 1 to 18 carbon atoms (e.g., methoxy,n-butoxy, n-octyloxy, methoxyethoxy, and benzyloxy), an aryloxy grouphaving 6 to 18 carbon atoms (e.g., phenoxy, p-tolyloxy,4-methoxyphenoxy, and 4-t-butylphenoxy), an alkoxycarbonyl group having2 to 19 carbon atoms (e.g., methoxycarbonyl, n-butoxycarbonyl,2-ethylhexyloxycarbonyl), or an aryloxycarbonyl group having 6 to 25carbon atoms. Among them, R₆ is more preferably an alkoxycarbonyl group,and most preferably n-butoxycarbonyl.

d is 0 or 1.

In the formula [S-3], Ar is preferably an aryl group having 6 to 24(preferably 6 to 18) carbon atoms (e.g., phenyl, 4-chlorophenyl,2,4-dichlorophenyl, 4-methoxyphenyl, 1-naphthyl, 4-n-butoxyphenyl,1,3,5-trimethylphenyl, and 2-(2-n-butoxycarbonylphenyl)phenyl). Amongthem, Ar is more preferably phenyl, 2,4-dichlorophenyl, or 2-(2-n-butoxycarbonyl phenyl)phenyl.

e is an integral number of 1 to 4 (preferably 1 to 3).

R₇ is preferably a hydrocarbon group having a valence of e and having 2to 24 (preferably 2 to 18) carbon atoms [e.g., the aliphatic groups aslisted for the above-described R₄, n-octyl, the aryl groups as listedfor the above-described R₄, —(CH₂)₂—,

] or hydrocarbon groups having a valence of e and having 4 to 24(preferably 4 to 18) carbon atoms which are linked each other by anether bond [e.g., —CH₂CH₂OCH₂CH₂—, —CH₂CH₂(OCH₂CH₂)₃—,—CH₂CH₂CH₂OCH₂CH₂CH₂—].

Among them, R₇ is more preferably an alkyl group, and most preferablyn-butyl, n-octyl, or 2-ethylhexyl.

In the formula [S-4], R₈ is preferably an aliphatic group having 1 to 24(preferably 1 to 17) carbon atoms (e.g., methyl, n-propyl,1-hydroxyethyl, 1-ethylpentyl, n-heptyl, n-undecyl, n-tridecyl,pentadecyl, 8,9-epoxy heptadecyl, cyclopropyl, cyclohexyl, and4-methylcyclohexyl). Among them, R₈ is most preferably n-heptyl,n-tridecyl, 1 -hydroxy ethyl, 1-ethylpentyl, or 8,9-epoxyheptadecyl.

f is an integral number of 1 to 4 (preferably 1 to 3).

R₉ is preferably a hydrocarbon group having a valence of f and having 2to 24 (preferably 2 to 18) carbon atoms, or hydrocarbon groups having avalence of f and 4 to 24 (preferably 4 to 18) carbon atoms which arelinked each other by an ether bond (e.g., the groups as listed for theabove-described R₇, 1-methyl-2-methoxyethyl, and 2-hexyldecyl). Amongthem, R₉ is most preferably 2-ethylhexyl, 2-hexyldecyl, or1-methyl-2-methoxyethyl.

In the formula [S-5], g is 2 to 4 (preferably 2 or 3).

R₁₀ is preferably a hydrocarbon group having a valence of g [forexample, —CH₂—, —(CH₂)₂—, —(CH₂)₄—, —(CH₂)₇—, or —(CH₂)₈—].

Among them, R₁₀ is most preferably, —(CH₂)₄— or —(CH₂)₈—.

R₁₁ is preferably an aliphatic group having 1 to 24 (preferably 4 to 18)carbon atoms, or aryl group having 6 to 24 (preferably 6 to 18) carbonatoms (e.g., the aliphatic groups and aryl groups as listed for theabove-described R4). Among them, R₁₁ is more preferably an alkyl group,and most preferably n-butyl, n-octyl, or 2-ethylhexyl.

In the formula [S-6], R₁₂ is preferably hydrogen atom, an aliphaticgroup having 1 to 24 (preferably 3 to 20) carbon atoms [e.g., n-propyl,1-ethyl pentyl, n-undecyl, n-pentadecyl, 2,4-di-t-pentylphenoxymethyl,4-t-octylphenoxymethyl, 3-(2,4-di-t-butylphenoxy)propyl,1-(2,4-di-t-butylpenoxy)propyl, cyclohexyl, 4-methylcyclohexyl, and8-N,N-diethylcarbamoyloctyl], or an aryl group having 6 to 24(preferably 6 to 18) carbon atoms (e.g., the aryl group as listed forthe above-described Ar, 3-methylphenyl, and2-(N,N-di-n-octylcarbamoyl)phenyl). Among them, R₁₂ is most preferablyn-undecyl, 8-N,N-diethylcarbamoyloctyl, 3-methylphenyl, or2-(N,N-di-n-octylcarbamoyl)phenyl.

R₁₃ and R₁₄ are each preferably hydrogen atom, an aliphatic group having1 to 24 (preferably 1 to 18) carbon atoms (e.g., methyl, ethyl,isopropyl, n-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-dodecyl,n-tetradecyl, cyclopentyl, and cyclopropyl), or an aryl group having 6to 18 (preferably 6 to 15) carbon atoms (e.g., phenyl, 1-naphthyl, andp-tolyl). Among them, R₁₃ and R₁₄ are each most preferably methyl,ethyl, n-butyl, n-octyl, n-tetradecyl, or phenyl. R₁₃ and R₁₄ may belinked each other to form a pyrrolidine ring, a piperidine ring, or amorpholine ring together with N. R₁₂ and R₁₃ may be linked each other toform a pyrrolidone ring or a piperidine ring together with N.

X is —CO— or —SO₂—, and preferably X is —CO—.

In the formula [S-7], R₁₅ is preferably an aliphatic group having 1 to24 (preferably 3 to 18) carbon atoms (e.g., methyl, isopropyl, t-butyl,t-pentyl, t-hexyl, t-octyl, 2-butyl, 2-hexyl, 2-octyl, 2-dodecyl,2-hexadecyl, t-pentadecyl, cyclopentyl, and cyclohexyl), analkoxycarbonyl group having 2 to 24 (preferably 5 to 17) carbon atoms(e.g., n-butoxycarbonyl, 2-ethylhexyloxycarbonyl, andn-dodecyloxycarbonyl), an aryloxycarbonyl group having 7 to 24(preferably 7 to 18) carbon atoms (e.g., phenoxycarbonyl group,naphthoxycarbonyl group, and cresyloxycarbonyl group), an alkylsulfonylgroup having 1 to 24 (preferably 1 to 18) carbon atoms (e.g.,methylsulfonyl, n-butylsulfonyl, and n-dodecylsulfonyl), an arylsulfonylgroup having 6 to 30 (preferably 6 to 24) carbon atoms (e.g.,p-tolylsulfonyl, p-dodecylphenylsulfonyl, andp-hexadecyloxyphenylsulfonyl), an aryl group having 6 to 32 (preferably6 to 24) carbon atoms (e.g., phenyl and p-tolyl), or a cyano group.Among them, R₁₅ is more preferably an aliphatic group having 1 to 24carbon atoms or an alkoxycarbonyl group having 2 to 24 carbon atoms, andmost preferably an aliphatic group having 1 to 24 carbon atoms.

R₁₆ is preferably a halogen atom (preferably Cl), an aliphatic grouphaving 1 to 24 (preferably 1 to 18) carbon atoms {more preferably, analkyl group (e.g., the alkyl group as listed for the above-describedR₁₅), a cycloalkyl group having 3 to 18 (more preferably 5 to 17) carbonatoms (e.g., cyclopentyl and cyclohexyl)}, an aryl group having 6 to 32(preferably 6 to 24) carbon atoms (e.g., phenyl and p-tolyl), an alkoxygroup having 1 to 24 (preferably 1 to 18) carbon atoms (e.g., methoxy,n-butoxy, 2-ethylhexyloxy, benzyloxy, n-dodecyloxy, n-hexadecyloxy), oran aryloxy group having 6 to 32 (preferably 6 to 24) carbon atoms (e.g.,phenoxy, p-t-butylphenoxy, p-t-octylphenoxy, m-pentadecylphenoxy, andp-dodecyloxyphenoxy). Among them, R₁₆ is more preferably an aliphaticgroup having 1 to 24 carbon atom, and most preferably an aliphatic grouphaving 1 to 12 carbon atoms.

h is an integral number of 1 to 2.

In the formula [S-8], preferable examples of R₁₇ and R₁₈ are the same asthose listed for the above-described R₁₃ and R₁₄ except for hydrogenatom. Among them, R₁₇ and R₁₈ are each more preferably an aliphaticgroup, and most preferably n-butyl, n-octyl, or n-dodecyl. R₁₇ and R₁₈cannot be linked each other to form a ring.

Preferable examples of R₁₉ are the same as those listed for theabove-described R₁₆. Among them, R₁₉ is more preferably an alkyl groupor an alkoxy group, and most preferably n-octyl, methoxy, n-butoxy, orn-octyloxy.

i is an integral number of 1 to 5.

In the formula [S-9], preferable examples of R₂₀ and R₂₁ are the same asthose listed for the above-described R₁, R₂, and R₃ when they do notform a ring. Among them, R₂₀ and R₂₁ are most preferably a substitutedor nonsubstituted aliphatic group having 1 to 24 carbon atoms. R₂₀ andR₂₁, may be linked each other to form a ring, and the formed ring haspreferably 3 to 10 members, and most preferably 5 to 7 members.

j represents 1 or 2, and preferably j is 1.

Specific examples of the high-boiling point organic solvent (compoundsS-1 to S-53), and the viscosity (measured at temperatures of 25° C. and60° C. using the above-described means; mPa·s) and boiling point (° C.)of the high-boiling point organic solvents are summarized below.

The boiling point of the high-boiling point organic solvents has beencalculated by converting from the boiling point during distillationunder reduced pressure to that under normal pressure. In the followingspecific examples, the compounds whose boiling point is not shown havebeen confirmed not to boil at 170° C., and the compounds whose viscosityat 25° C. is not shown are solid at 25° C.

Boiling Viscosity (mPa · s) Point (25° C.) (60° C.) (° C.) Compoundsrepresented by the formula [S-1] S-1

— 8.3 370 S-2

57.6 11.8 435 S-3

95 17.5 485 S-4

65 12.8 435 S-5

49 10.3 435 S-6

11.7 4.0 390 S-7

20.22 5.8 420 S-8 O═P(OC₁₂H₂₅(n))₃ 28.6 6.9 480 S-9 O═P(OC₆H₁₃(n))₃ 6.623.0 365 S-10 O═P(OCH₂CH₂Cl)₃ 20.8 5.5 360 S-11 O═P(OCH₂CH₂OC₄H₉(n))₃10.9 3.8 400 S-12 ((EH)C₈H₁₇)₃P═O 41.1 9.0 — S-13

13.7 4.3 — Compounds represented by the formula [S-2] S-14

20.3 5.1 370 S-15

34.9 8.0 380 S-16

62.7 11.7 400 S-17

52.1 10.8 — S-18

42 9.1 335 S-19

74 14.2 355 S-20

55.7 13.1 400 Compounds represented by the formula [S-3] S-21

5.68 2.4 300 S-22

11.44 3.9 360 S-23

51.1 10.6 — Compounds represented by the formula [S-4] S-24

7.17 3.1 380 S-25

39.84 8.8 — S-26

22.83 5.9 — S-27

12 4.0 — S-28

41.4 9.0 430 S-29

47.3 10.0 440 Compounds represented by the formula [S-5] S-30

11.7 4.3 390 S-31

19.9 6.1 410 S-32 (n)C₄H₉OCO(CH₂)₈COOC₄H₉(n) 8.09 3.5 345 S-33

88.9 16.5 — S-34

37.50 8.4 440 S-35

42.7 9.3 390 Compounds represented by the formula [S-6] S-36

9.45 3.6 340 S-37

45.8 9.8 — S-38

20.0 5.4 350 S-39

12.83 4.2 320 S-40

77.1 14.7 — S-41 (C₂H₅)₂—NCO—(CH₂)₈—CON(C₂H₅)₂ 40.7 8.9 405 S-42

49.65 10.4 — Compounds represented by the formula [S-7] S-43

92 16.9 — Compounds represented by the formula [S-8] S-44

15.5 4.6 — S-45

27.1 6.6 — S-46

35.3 8.0 — S-47

79.14 15.0 — Compounds represented by formula [S-9] S-48

37.62 8.4 — S-49

43.1 9.3 — Other Compounds S-50 C_(n)H_(2n+1) (a mixture of n-paraffin n= 14 and 15) 2.47 0.4 260 (For example, product name NP-SH: manufacturedby Mitsui-Texaco Chemicals Co., Ltd.) S-51

35.85 8.1 330 S-52

45.9 9.8 — S-53

25.82 6.7 —

The high-boiling point organic solvent may be used alone or incombination of two or more thereof [e.g., tticresylphosphate and dibutylphthalate, trioctylphosphate and di(2-ethylhexyl)sebacate, dibutylphthalate and poly(N-t-butylacrylamide)].

Other examples of the high-boiling point organic solvents except for theabove-described compounds, and /or the method for synthesizing thesehigh-boiling point organic solvents are, for example, described in U.S.Pat. Nos. 2,322,027, 2,533,514, 2,772,163, 2,835,579, 3,594,171,3,676,137, 3,689,271, 3,700,454, 3,748,141, 3,764,336, 3,765,897,3,912,515, 3,936,303, 4,004,928, 4,080,209, 4,127,413, 4,193,802,4,207,393, 4,220,711, 4,239,851, 4,278,757, 4,353,979, 4,363,873,4,430,421, 4,430,422, 4,464,464, 4,483,918, 4,540,657, 4,684,606,4,728,599, 4,745,049, 4,935,321, and 5,013,639, European PatentApplication Laid-Open (EP-A) Nos. 276,319A, 286,253A, 289,820A,309,158A, 309,159A, 309,160A, 509,311A, and 510,576A, East German PatentNos. 147,009, 157,147, 159,573, and 225,240A, U.K. Patent No.2,091,124A, and JP-A Nos. 48-47335, 50-26530, 51-25133, 51-26036,51-27921, 51-27922, 51-149028, 52-46816, 53-1520, 53-1521, 53-15127,53-146622, 54-91325, 54-106228, 54-118246, 55-59464, 56-64333, 56-81836,59-204041, 61-84641, 62-118345, 62-247364, 63-167357, 63-214744,63-301941, 64-9452, 64-9454, 64-68745, 1-101543, 1-102454, 2-792,2-4239, 2-43541, 4-29237, 4-30165, 4-232946, and 4-346338.

In the present invention, high-boiling point organic solvents having aboiling point higher than 100° C. are preferable, and high-boiling pointorganic solvents having a boiling point higher than 170° C. are morepreferable.

The amount of the addition of the lipophilic solvent to the secondliquid is preferably in the range of 50% by mass to 100% by mass, morepreferably 70% by mass to 100% by mass, and most preferably 90% by massto 100% by mass based on the total weight of the liquid.

The second liquid B preferably contains a polymerization initiator. Morepreferably, the second liquid B additionally contains a lipophilicsolvent, and as necessary, may contain a colorant, a polymerizablematerial and/or other components. Details of the polymerizable materialare as described above.

<Polymerization Initiator>

The second liquid B can appropriately contain at least onepolymerization initiator. The polymerization initiator is a compoundwhich generates initiating species such as a radical by the applicationof activation light and/or heat, thereby initiates and promotes thepolymerization or crosslinking reaction of a polymerizable orcrosslinkable material to cure the material.

The polymerization initiator is preferably contained in isolation frompolymerizable material from the viewpoint of securing the storagestability of the aforementioned first liquid A and the second liquid B.In the present invention, the polymerization initiator is preferablycontained not in the first liquid A containing the polymerizablematerial but in the second liquid B or any other liquids.

The polymerization initiator may be selected from knownphotopolymerization initiators (including radical generators), heatpolymerization initiators, and compounds having a bond whosedissociation energy is low.

Examples of the photopolymerization initiator (including radicalgenerator) include organic halogenated compounds, carbonyl compounds,organic peroxide compounds, azo-based polymerization initiators, azidocompounds, metallocene compounds, hexaarylbiimidazol compounds, organicborate compounds, disulfate compounds, and onium salt compounds.

Preferable examples of the polymerization initiator include followingphotopolymerization initiators.

Examples of the photopolymerization initiator include acetophenonederivatives, benzophenone derivatives, benzyl derivatives, benzoinderivatives, benzoin ether derivatives, benzyldialkylketal derivatives,thioxanthone derivatives, acylphosphine oxide derivatives, metalcomplexes, p-dialkylamino benzoic acid, azo compounds, and peroxidecompounds. Among them, acetophenone derivatives, benzyl derivatives,benzoin ether derivatives, benzyldialkylketal derivatives, thioxanthonederivatives, and acylphosphine oxide derivatives are preferable, andacetophenone derivatives, benzoin ether derivatives, benzyldialkylketalderivatives, and acyl phosphine oxide derivatives are most preferable.

Specific examples of the above-described photopolymerization initiatorinclude acetophenone, 2,2-diethoxyacetophenone,p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, benzophenone,p,p′-dichlorobenzophenone, p,p′-bisdiethylaminobenzophenone, Michlerketone, benzyl, benzoin, benzoin methyl ether, benzoin isopropyl ether,benzoin-n-propyl ether, benzoin isobutyl ether, benzyl dimethyl ketal,1-hydroxy-cyclohexyl phenyl ketone, tetramethylthiuram monosulfide,thioxanthone, 2-chlorothioxanthone, 2,4-dimethyl thioxanthone,2,2-dimethylpropioyldiphenylphosphine oxide,2-methyl-2-ethylhexanoyldiphenylphosphine oxide,2,6-dimethylbenzoyldiphenylphosphine oxide,2,6-dimethoxybenzoyldiphenylphosphine oxide,2,4,6-trimethylbenzoyldiphenylphosphine oxide,bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide,2,3,6-trimethylbenzoyl-diphenylphosphine oxide,bis(2,3,6-trimethylbenzoyl)-phenylphosphine oxide,2,4,6-trimethoxybenzoyl-diphenylphosphine oxide,2,4,6-trichlorobenzoyldiphenylphosphine oxide,2,4,6-trimethylbenzoylnaphthyl phosphonate,bis(η⁵-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium, p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid,azobisisobutyronitrile, 1,1′-azobis(1-acetoxy-1-phenylethane), benzoinperoxide, and di-tert-butyl peroxide.

In addition to the above-described compounds, other preferable examplesof the photopolymerization initiator are described in “Shigaisen KokaSystem (Ultraviolet Curing System)”, Kiyoshi Kato (Sogo Gijutsu Center,1989) p. 65 to 148.

The polymerization initiator is preferably excellent in sensitivity. Forexample, polymerization initiators which cause thermal decomposition ata temperature of 80° C. or lower are not preferable from the viewpointof storage stability.

The polymerization initiator may be used alone or in combination two ormore thereof. Furthermore, known sensitizers also may be used for thepurpose of improving sensitivity in the range that the effect of thepresent invention may not be impaired.

When the first liquid A and the second liquid B are jetted on a mediumat the maximum amount required for image formation, the content of thepolymerization initiator in the second liquid B is preferably 0.5 to 20%by mass, more preferably 1 to 15% by mass, and most preferably 3 to 10%by mass based on the polymerizable material per unit area, from theviewpoint of temporal stability, curability, and curing rate. If thecontent is excessive, precipitation or separation may occur with time,and ink properties such as strength and scratch resistance may bedeteriorated after curing.

When a polymerization initiator is contained in the aforementioned thefirst liquid A as well as the second liquid B in the appropriate rangethat the storage stability of the first liquid A is maintained at adesired degree.

The polymerization initiator may be contained not in the second liquid Bbut in the aforementioned first liquid A. In this instance, the contentin the first droplet is preferably 0.5 to 20% by mass, and morepreferably 1 to 15% by mass based on the polymerizable or crosslinkingcompound in the first liquid A.

<Colorant>

At least one type of colorant may be contained in the aforementionedfirst liquid A to allow the formation of a single-color or multi-colorvisible image.

The colorant may be contained in the second liquid B or other liquids.

The colorant is not particularly limited, and can be selected asappropriate from known water soluble dyes, oil-soluble dyes, pigmentsand the like. Among them, oil-soluble dyes and pigments which areuniformly dispersible and soluble in an water-insoluble medium arepreferable, because the first liquid A and the second liquid B accordingto the present invention are preferably composed on the basis of anwater-insoluble organic solvent from the viewpoint of the effect of thepresent invention. The oil-soluble dyes and pigments which can beappropriately used in the present invention are further described below.

—Oil-Soluble Dye—

The oil-soluble dye is not particularly limited, and can be selectedfrom optional ones. Examples of the oil-soluble dye are listed below foreach hue.

Examples of yellow dyes include aryl or heteryl-azo dyes having aphenol, a naphthol, an aniline, a pyrazolone, a pyridone, or anopen-ring active methylene compound as the coupling component;azomethine dyes having an open-ring active methylene compound as thecoupling component; methine dyes such as benzylidene dyes andmonomethineoxonol dyes; and quinone-based dyes such as naphthoquinonedyes and anthraquinone dyes. Other examples of the dye includequinophthalone dyes, nitro and nitroso dyes, acridine dyes, andacridinon dyes.

Examples of magenta dyes include aryl or heteryl-azo dyes having aphenol, a naphthol, or an aniline as the coupling component; azomethinedyes having a pyrazolone or a pyrazolotriazole as the couplingcomponent; methine dyes such as arylidene dyes, styryl dyes, melocyaninedyes, and oxonol dyes; carbonium dyes such as diphenylmethane dyes,triphenylmethane dyes, and xanthene dyes, quinone-based dyes such asnaphthoquinone, anthraquinone, and anthrapyridone, and condensedpolycyclic dyes such as dioxazine dyes.

Examples of cyan dyes include indoaniline dyes, indophenol dyes, orazomethine dyes having a pyrrolotriazole as the coupling component;polymethine dyes such as cyanine dyes, oxonol dyes, and melocyaninedyes; carbonium dyes such as diphenylmethane dyes, triphenylmethanedyes, and xanthene dyes; phthalocyanine dyes; anthraquinone dyes; arylor heteryl-azo dyes having a phenol, a naphthol, or an aniline as thecoupling component, and indigo and thioindigo dyes.

The above-described dyes may develop an yellow, magenta, or cyan coloronly after a portion of the color atomic group (chromophore) isdissociated. In this instance, the counter cation may be an inorganiccation such as an alkali metal or ammonium, or an organic cation such aspyridinium and a quaternary ammonium salt, and may be a polymer cationhaving such a cation in the substructure.

When an oil-soluble dye is used as the colorant, the content of theoil-soluble dye in the first liquid A is preferably in the range of 0.05to 20% by mass, more preferably 0.1 to 15% by mass, and most preferably0.2 to 6% by mass based on the mass of total solids. Furthermore, whenthe oil-soluble dye is contained in the second liquid B or otherliquids, the content of the oil-soluble dye in each liquid is preferablyin the range of 0 to 1% based on the mass of total solids.

—Pigment—

It is also a preferable embodiment that a pigment used as the colorantbecause mixing of a plurality of liquid tends to form aggregates. As thepigment, either organic pigments or inorganic pigments may be used.Preferable examples of black pigments include carbon black pigments.Pigments of black and three primary colors of cyan, magenta, and yelloware usually used, and other pigments having a hue of, for example, red,green, blue, brown, or white, metallic pigments such as gold and silverpigments, and colorless or light-colored extender pigments may be usedaccording to the intended use.

Furthermore, particles such as silica, alumina, and resin particlessurface-coated with a dye or a pigment, insoluble lake dyes, coloremulsions, color latexes and the like may be used as the pigment. Inaddition, resin-coated pigments also may be used. They are calledmicrocapsule pigments, and products of Dainippon Ink And Chemicals,Incorporated, Toyo Ink Mfg. Co., Ltd., and others are commerciallyavailable.

The volume average particle size of the pigment particles contained inthe liquid is preferably in the range of 10 to 250 nm, more preferablyin the range of 50 to 200 nm from the viewpoint of the balance betweenoptical density and storage stability. The volume average particle sizeof the pigment particles can be measured with a measuring apparatus suchas LB-500 (manufactured by Horiba, Ltd.).

When a pigment is used as the colorant, the content of the pigment inthe first liquid A is preferably in the range of 0.1 to 20% by mass, andmore preferably in the range of 1 to 10% by mass based on the mass oftotal solids from the viewpoints of optical density and ejectionstability. Furthermore, when a pigment is contained in the second liquidB or other liquids, the content of the pigment in each liquid ispreferably in the range of 0 to 1% by mass based on the mass of totalsolids.

Colorants may be used alone or in combination or two or more thereof.Furthermore, the colorants may be different or the same among jetteddroplets and liquids.

In the present invention, examples of the preferable embodiment include:

(1) an embodiment in which the first liquid A contains a polymerizablematerial, the second liquid B contains a polymerization initiator;

(2) an embodiment in which the first liquid A contains a polymerizablematerial and a colorant, and the second liquid B contains apolymerization initiator; and

(3) an embodiment in which the first liquid A contains a polymerizablematerial and a colorant, the second liquid B contains a polymerizationinitiator and a lipophilic solvent.

In the above-described embodiments, the polymerizable material may becontained in the first liquid A as well as in the second liquid B in therange that the effect of the present invention may not be impaired, andthe polymerization initiator may be contained in the second liquid Baccording to the present invention, as well as in the first liquid A inthe range that the effect of the present invention may not be impaired.

<Other Components>

In addition to the above-described components, known additives or thelike may be added in accordance with the intended use.

—Storage Stabilizer—

Storage stabilizers may be added to the first liquid A and the secondliquid B (preferably the first liquid A) according to the presentinvention for the purpose of inhibiting undesirable polymerizationduring storage. The storage stabilizers are preferably used incombination with polymerizable or crosslinkable materials, and arepreferably soluble in the contained droplets or liquids, or othercoexisting components.

Examples of the storage stabilizer include quaternary ammonium salts,hydroxy amines, cyclic amides, nitrites, substituted ureas, heterocyclecompounds, organic acids, hydroquinone, hydroquinone monoethers, organicphosphines, and copper compounds. Specific examples thereof includebenzyltrimethylammonium chloride, diethylhydroxylamine, benzothiazole,4-amino-2,2,6,6-tetramethylpiperidine, citric acid, hydroquinonemonomethyl ether, hydroquinone monobutyl ether, and copper naphthenate.

The amount of addition of the storage stabilizer is preferably adjustedon the basis of the activity of the polymerization initiator,polymerizability of the polymerizable or crosslinkable material, and thekind of the storage stabilizer, and preferably 0.005 to 1% by mass, morepreferably 0.01 to 0.5% by mass, and further preferably 0.01 to 0.2% bymass on the basis of the solid content in the liquid, from the viewpointof the balance between the storage stability and curability.

—Electro-Conductive Salts—

Electro-conductive salts are solid compounds for improvingelectro-conductivity. In the present invention, it is preferable not tosubstantially use the salts because they tend to precipitate duringstorage. However, they may be added in an appropriated amount when thesolubility is improved by increasing the solubility ofelectro-conductive salts or using liquid components with highsolubility.

Examples of the above-described electro-conductive salts includepotassium thiocyanate, lithium nitrate, ammonium thiocyanate, anddimethylamine hydrochloride salt.

—Solvent—

In the present invention, solvents other than the above-describedhigh-boiling solvents may be used. The solvents can be used for thepurposes of improving the polarity, viscosity, and surface tension ofthe liquid (ink), improving the solubility and dispersibility of thecoloring materials, adjusting electro-conductivity, and adjustingprinting performance.

The solvents are preferably water-insoluble liquids containing noaqueous solvent for quick-drying properties and recording a high qualityimage having a uniform line width, thus they preferably comprise anabove-described high-boiling point organic solvent.

Examples of the solvent include low-boiling organic solvents having aboiling point of 100° C. or lower, but it is preferable not use suchlow-boiling organic solvents because they may affect the curability andmay cause environmental pollution. If a low-boiling organic solvent isused, it is preferable to use a highly safe one. Highly safe solventsare solvents for which a high control concentration (an index defined inthe work environmental evaluation criteria) has been defined. Thecontrol concentration is preferably 100 ppm or higher, more preferably200 ppm or higher. Examples of the highly safe solvents includealcohols, ketones, esters, ethers, and hydrocarbon, and specificexamples thereof include methanol, 2-butanol, acetone,methylethylketone, ethyl acetate, and tetrahydrofuran.

The solvents may be used alone or in combination of two or more thereof.However, when water and/or a low-boiling organic solvent is used, thecontent of them in each liquid is preferably 0 to 20% by mass, morepreferably 0 to 10% by mass, and most preferably substantially free. Itis not preferable that the first liquid A and the second liquid Baccording to the present invention contain water from the viewpoints oftemporal stability such as development of unevenness with time, anddevelopment of liquid turbidity due to precipitation of dyes, and dryingproperties on an impermeable or slowly-permeable recording medium.Substantially free means that the presence of inevitable impurities areacceptable.

—Other Additives—

Furthermore, known additives such as a polymer, a surface tensionadjuster, an ultraviolet absorbing agent, an antioxidant, an antifadingagent, and pH adjuster may be used.

The known surface tension adjuster, ultraviolet absorbing agent,antioxidant, antifading agent, and pH adjuster may be used asappropriate. Specific examples thereof include the additives asdescribed in JP-A No. 2001-181549.

In addition to the above-described compounds, a pair of compounds whichreact with each other by mixing to form an aggregate or thicken may beseparately contained in the first liquid A and the second liquid Baccording to the present invention. The above-described pair ofcompounds have properties of rapidly forming an aggregate or rapidlythickening the liquid, thereby coalescence between adjacent droplets ismore effectively inhibited.

Examples of the reaction between the above-described pair of compoundsinclude an acid-base reaction, a hydrogen bond reaction between acarboxylic acid and an amide group-containing compound, a crosslinkingreaction such as those between boronic acid and a diol, and a reactionby electrostatic interaction between a cation and an anion.

EXAMPLES

The present invention will be described in more detail with reference tothe following examples, but the present invention is not construed asbeing limited thereto.

Example 1

<Preparation of Pigment Dispersion>

16 g of PB15:3 (trade name: IRGALITE BLUE GLO, manufactured by CibaSpecialty Chemicals), 48 g of 1,6-hexanediol diacrylate (trade name:HDDA, manufactured by Daicel-Cytec Company Ltd., and 16 g of BYK-168(manufactured by BYK-Chemie) were mixed, and stirred for one hour with astirrer. The mixture after stirring was dispersed with an Eiger mill toobtain a pigment dispersion P-1.

The dispersion was carried out for 1 hour together with zirconia beadshaving a diameter of 0.65 mm filled at a filling rate of 70%, and at aperipheral speed of 9 m/s.

<Preparation of Ink Jet Recording Liquid I-1 Containing Pigment>

Components of the following composition were mixed and stirred todissolve them, thereby a ink jet recording liquid I-1 was prepared. Thesp value of the ink jet recording liquid I-1 was 20.

The above-described pigment dispersion P-1   10 g DPCA 60 (polymerizablecompound, manufactured by Nippon 0.54 g Kayaku Co., Ltd.) 1,6-hexanedioldiacrylate (polymerizable compound) (trade 9.46 g name: HDDA,manufactured by Daicel-Cytec Company Ltd.)

The sp value was calculated using the aforementioned sp valuecalculation program by R. L. Smith (Tohoku University) (25° C).Hereinafter the same will employ. Compounds which don't have carbon atomwere excluded from the calculation, and constitutional units such aspolymer and polyethylene chains were treated as saturated repeatingunits having dangling bonds. Water was calculated as 47.8.

<Preparation of Liquid II-1 for Ink Jet Recording Without Pigment>

Components of the following composition were mixed and stirred todissolve them, thereby an ink jet recording liquid II-1 was prepared.The sp value of the liquid II-1 is summarized in Table 1.

High-boiling point organic solvent (aforementioned compound 17.4 g S-8)Polymerization initiator -1 (TPO-L) shown below  2.6 g

Polymerization Initiator 1<Preparation of Liquids II-2 to II-4 for Ink Jet Recording WithoutPigment>

The ink jet recording liquids II-2 to II-4 were prepared in the samemanner as the above-described liquid II-1, except that the high-boilingpoint organic solvent (compound S-8) was replaced with each of organicsolvents shown in the following Table 1. The sp value of the liquidsII-1 to II-4 are summarized in Table 1.

TABLE 1 High-boiling point organic solvent SP value II-1 S-8 18 II-2S-15 20 II-3 S-25 19 II-4 HDDA 20<Preparation of Comparative Ink Liquid I-0 for Ink Jet Recording>

Components of the following composition were mixed and stirred todissolve them, thereby a comparative ink jet recording liquid I-0 wasprepared. The sp value of the comparative ink liquid I-0 was 19.

The above-described pigment dispersion P-1   20 g DPCA 60 (polymerizablecompound, manufactured by 0.54 g Nippon Kayaku Co., Ltd.) High-boilingpoint organic solvent (aforementioned 16.86 g  compound S-1) Theabove-described Polymerization initiator -1 (TPO-L)  2.6 g<Preparation of Comparative Ink Liquid II-00>

Components of the following composition were mixed and stirred todissolve them, thereby a comparative ink liquid II-00 was prepared. Thesp value of the comparative ink liquid II-00 was 38.

Glycerin 17.4 g The above-described polymerization initiator -1 (TPO-L) 2.6 g<Preparation of Comparative Ink Liquid I-01>

Components of the following composition were mixed and stirred todissolve them, thereby a comparative ink liquid I-01 was prepared. Thesp value of the comparative ink liquid I-01 was 44. As the pigment wasnot dissolved, it was excluded from the calculation of the sp value.

Aqueous pigment dispersion

PB 15:3 10.5 g Styrene/acryl polymer (molar ratio 20/80) 3.15 gN-methylpyrrolidone   5 g Isopropylalcohol   5 g Water 76.3 g<Preparation of Comparative Ink Liquid II-01>

Components of the following composition were mixed and stirred todissolve them, thereby a comparative ink liquid II-01 was prepared. Thesp value of the comparative ink liquid II-01 was 38.

A-TMPT-3EO (manufactured by Shin-nakamura Chemical 10 g Co., Ltd.) Water60 g Isopropyl alcohol 30 g<Image Recording and Evaluation>

The ink jet recording liquids I-1 and II-1 prepared as described abovewere loaded into an ink jet printer (test model IJET 1000R2 head type,manufactured by Microjet, deposition frequency: 1 KHz, number ofnozzles: 64, double array, droplet size: about 70 pl), and ejected fromeach of the two heads in line shape. As the recording medium, apolyethylene terephthalate (PET) sheet having a thickness of 60 μm(trade name: PPL/Xerox Film OHP FILM for laser printer, manufactured byFuji Xerox Co., Ltd.; hereinafter referred to as PET sheet.), and artpaper (trade name: Tokubishi Art Ryomen, manufactured by MitsubishiPaper Mills Ltd.) were used.

The liquid II-1 and ink jet recording liquid I-1 were ejected at ajetting time interval of 400 m seconds. The liquid II-1 (the secondliquid B) was ejected, subsequently the ink jet recording liquid I-1(the first liquid A) was ejected so as to overlap the liquid II-1. Theejection frequency was adjusted in such a manner that the overlap ratiobetween the adjacent droplets of the liquid II-1 was 5%, and the overlapratio between the adjacent droplets (the first droplet a1 and the firstdroplet a2) of the liquid I-1 for the ink jet recording was 50%.

Furthermore, the overlap ratio of the ink jet recording liquid I-1 waschanged from 50% to 0%, and ejection was carried out in the same manneras described above.

Furthermore, the above-described jetting time interval was changed from400 m seconds to 2 seconds, and the ink jet recording liquid I-1 wasejected in the same manner as described above at the overlap ratio of50% and 0%.

The overlap ratio was, as aforementioned, calculated by the formula100×(2b-c)/2b [%], wherein b is the radius of one droplet at one secondafter deposition, and c is the distance between the adjacent jetteddroplets.

Furthermore, the liquid II-2, liquid II-3, liquid II-4, and thecomparative ink solution II-00 (Comparative Example) prepared above werereplaced with the above-described liquid II-1, and ejected in line formin the same manner as described above.

As Comparative Examples, the comparative ink solutions I-01 and II-01were replaced with the ink jet recording liquids I-1 and II-1, andejected in line shape in the same manner as described above.

Furthermore, as another Comparative Example (one-liquid type), ejectionwas carried out in the same manner as described above except that thecomparative ink solution I-0 was replaced with the ink jet recordingliquid I-1, and the liquid II-1 was not used.

After ejection, ultraviolet light was exposed by a metal halide lamp atan wavelength of 365 nm and light exposure of 500 mJ/cm², therebyrecording an image. The obtained image was subjected to the followingevaluations. The evaluation results are summarized in the followingTables 2 and 3. For the liquids prepared as described above, the liquids“I-” are referred to as the liquid I (the first liquid A), and theliquids “II-” are referred to as the liquid II (the second liquid B).

—1. Evaluation of Line Quality—

The liquids I and II were overlappedly jetted in line shape, and theline quality was evaluated in accordance with the following evaluationcriteria. For the comparative ink solution I-0, only one kind of liquidwas jetted in line shape.

<Evaluation criteria>

A: Dot shape was maintained, and uniform line shape was obtained.

A′: Dot shape was not maintained, but uniform line shape was obtained.

B: Each dot lacked independence, and uneven line width was observed atsome points, because of the coalescence between adjacent droplets.

C: Dots lacked independence, and uneven line width was observed all overthe surface, because of the coalescence between adjacent droplets wasobserved all over the surface.

—2. Evaluation of Density—

The density of linear image recorded on a PET sheet was measured with amicrodensitometer (trade name: MICRO-PHOTOMETER MPM-No.172, manufacturedby Union Optical Co., Ltd.), and the results were evaluated according tothe following evaluation criteria. The evaluation of density was carriedout only for the images on PET sheets.

<Evaluation criteria>

A: Density was 2.5 or more.

B: Density was 2.0 or more and below 2.5.

C: Density was 1.5 or more and below 2.

D: Density was below 1.5.

—3. Evaluation of Stickiness—

Immediately after ultraviolet irradiation, the image surface (recordedsurface) was touched with fingers, and evaluated in accordance with thefollowing evaluation criteria.

<Evaluation criteria>

A: No stickiness.

B: Some stickiness was detected.

C: Significant stickiness was detected.

—4. Evaluation of Rubbing Resistance—

An image was formed by jetting each ink on each of a PET sheet and artpaper in the above manner. When 30 minutes lapsed since the imageformation, the image portion(s) of the image was rubbed with an eraserby moving the eraser back and forth ten times. The degree of imagedensity decrease after the rubbing was determined on the basis of thefollowing criteria.

<Evaluation criteria>

A: The image density after the rubbing is not different from that beforethe rubbing.

B: The difference between the image density before the rubbing and thatafter the rubbing is slight.

C: The difference between the image density before the rubbing and thatafter the rubbing is significant.

—5. Evaluation of Light Resistance—

The line images recorded on PET sheets were irradiated with xenon light(85,000 Lux) for one week using an weather meter (trade name: AtlasC.I65), and the density before and after irradiation was measured with amicrodensitometer (trade name: MICRO-PHOTOMETER MPM-No.172, manufacturedby Union Optical Co., Ltd.) to determine the dye residual rate [%]. Theresults were evaluated according to the following five-grade evaluationcriteria. The evaluation of light resistance was carried out only forthe image on PET sheets.

<Evaluation criteria>

A: The colorant remaining rate was 90% or more.

B: The colorant remaining rate was 89 to 80%.

C: The colorant remaining rate was 79 to 70%.

D: The colorant remaining rate was 69 to 50%.

E: The colorant remaining rate was less than 49%.

—6. Evaluation of Ozone Resistance—

The line images recorded on PET sheets were stored for one week at aozone density of 5.0 ppm, and the image density before and after thestorage was measured with a microdensitometer (trade name:MICRO-PHOTOMETER MPM-No. 172, manufactured by Union Optical Co., Ltd.)to determine the dye residual rate [%]. The results were evaluatedaccording to the following five-grade evaluation criteria. Theevaluation of ozone resistance was carried out only for the images onPET sheets.

<Evaluation criteria>

A: Dye residual rate was 90% or more.

B: Dye residual rate was 89 to 80%.

C: Dye residual rate was 79 to 70%.

D: Dye residual rate was 69 to 50%.

E: Dye residual rate was less than 49%.

TABLE 2 Jetting time Interval between two Overlap Recording RubbingLight Ozone Liquids Ratio Medium Line Quality Density StickinessResistance Resistance Resistance Remark II-1

I-1 400 ms 50% PET A A A A A A The present invention II-1

I-1 400 ms 50% Art paper A — A A — — The present invention II-2

I-1 400 ms 50% PET A A A A A A The present invention II-2

I-1 400 ms 50% Art paper A — A A — — The present invention II-3

I-1 400 ms 50% PET A A A A A A The present invention II-3

I-1 400 ms 50% Art paper A — A A — — The present invention II-4

I-1 400 ms 50% PET A A A A A A The present invention II-4

I-1 400 ms 50% Art paper A — A A — — The present invention I-0 400 ms50% PET C A A A A A Comparative example I-0 400 ms 50% Art paper C — A A— — Comparative example II-00

I-1 400 ms 50% PET C C C C A A Comparative example II-00

I-1 400 ms 50% Art paper C — C C — — Comparative example II-01

I-01 400 ms 50% PET C A C C A A Comparative example II-01

I-01 400 ms 50% Art paper C — C C — — Comparative example II-1

I-1 400 ms  0% PET A C A A A A Comparative example II-1

I-1 400 ms  0% Art paper A — A A — — Comparative example II-2

I-1 400 ms  0% PET A C A A A A Comparative example II-2

I-1 400 ms  0% Art paper A — A A — — Comparative example II-3

I-1 400 ms  0% PET A C A A A A Comparative example II-3

I-1 400 ms  0% Art paper A — A A — — Comparative example II-4

I-1 400 ms  0% PET A C A A A A Comparative example II-4

I-1 400 ms  0% Art paper A — A A — — Comparative example I-0 400 ms  0%PET  A′ C A A A A Comparative example I-0 400 ms  0% Art paper  A′ — A A— — Comparative example II-00

I-1 400 ms  0% PET C D C C A A Comparative example II-00

I-1 400 ms  0% Art paper B — C C — — Comparative example II-01

I-01 400 ms  0% PET C C C C A A Comparative example II-01

I-01 400 ms  0% Art paper C — C C — — Comparative example

TABLE 3 Jetting time Interval between two Overlap Recording Line RubbingLight Ozone Liquids Ratio Medium Quality Density Stickiness ResistanceResistance Resistance Remark II-1

I-1 2 s 50% PET A A A A A A The present invention II-1

I-1 2 s 50% Art paper B — A A — — The present invention II-2

I-1 2 s 50% PET A A A A A A The present invention II-2

I-1 2 s 50% Art paper B — A A — — The present invention II-3

I-1 2 s 50% PET A A A A A A The present invention II-3

I-1 2 s 50% Art paper B — A A — — The present invention II-4

I-1 2 s 50% PET A A A A A A The present invention II-4

I-1 2 s 50% Art paper B — A A — — The present invention I-0 2 s 50% PETC A A A A A Comparative example I-0 2 s 50% Art paper C — A A — —Comparative example II-00

I-1 2 s 50% PET C C C C A A Comparative example II-00

I-1 2 s 50% Art paper C — C C — — Comparative example II-01

I-01 2 s 50% PET C A C C A A Comparative example II-01

I-01 2 s 50% Art paper C — C C — — Comparative example II-1

I-1 2 s  0% PET A C A A A A Comparative example II-1

I-1 2 s  0% Art paper A — A A — — Comparative example II-2

I-1 2 s  0% PET A C A A A A Comparative example II-2

I-1 2 s  0% Art paper A — A A — — Comparative example II-3

I-1 2 s  0% PET A C A A A A Comparative example II-3

I-1 2 s  0% Art paper A — A A — — Comparative example II-4

I-1 2 s  0% PET A C A A A A Comparative example II-4

I-1 2 s  0% Art paper A — A A — — Comparative example I-0 2 s  0% PET A′ C A A A A Comparative example I-0 2 s  0% Art paper  A′ — A A — —Comparative example II-00

I-1 2 s  0% PET C D C C A A Comparative example II-00

I-1 2 s  0% Art paper C — C C — — Comparative example II-01

I-01 2 s  0% PET A C A A A A Comparative example II-01

I-01 2 s  0% Art paper A — A A — — Comparative example

In the Tables 1 and 2, when II-4 was used, the ejectability wasdeteriorated to some extent in a repeated test. In the evaluation of theTables 1 and 2, “-” means that evaluation wasn't subjected.

In the embodiment, as shown in the above Tables 2 and 3, coalescencebetween the droplets which had been overlappedly jetted in contact witheach other was prevented, thereby a sharp line image with a maintaineddot shape was obtained at a high density.

On the other hand, in Comparative Example of a one-liquid system usingthe comparative ink I-0, higher overlap ratios resulted in deterioratedline quality, and the decrease in the overlap ratio resulted in someequalization of the line quality to some extent though the dot shape wasnot maintained. However, a high density image was not obtained.

In Comparative Examples using the comparative ink solutions II-01(water-based) and II-00, which had a sp value out of the range of theembodiment, the line quality was inferior, and the stickiness andrubbing resistance were also inferior. In case of the combination of I-1and II-0 whose the sp values were significantly different from eachother and out of the range of the embodiment, the decrease in thedensity presumably due to the collapse of dispersed pigments, and thedeterioration of the film quality presumably due to the poor dispersionof the polymerization initiator were observed. Accordingly, it wasimpossible to form an image with a good line quality and a high density.

Furthermore, when the jetting time interval was 400 m seconds, imagerecording with a better line quality was achieved specifically on artpaper, in comparison with the instance where the jetting time intervalwas reduced to 2 seconds.

When the liquid I-0 remained in an ink jet head for one day, clogging ofthe nozzle was observed.

Example 2

An experimental apparatus equipped with a CB1 head (manufactured byToshiba Tech Corporation, number of nozzles: 318, density of nozzles:150 npi, drop size: 6 pl, driving frequency: 4.8 kHz) was replaced withthe ink jet printer in Example 1, and a line-form image was formed usingthe apparatus in the same manner as Example 1. As a result, a thin lineof independent dots was formed.

The foregoing description of the embodiments of the present inventionhas been provided for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Obviously, many modifications and variationswill be apps rent to practitioners skilled in the art. The embodimentswere chosen and described in order to best explain the principles of theinvention and its practical applications, thereby enabling othersskilled in the art to understand the invention for various embodimentsand with the various modification s as are suited to the particular usecontemplated. It is intended that the scope of the invention be definedby the following claims and their equivalents. All publications, patentapplications, and technical standards mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication, patent application, or technical standard wasspecifically and individually indicated to be incorporated by reference.

1. An ink jet recording method for recording an image on a recordingmedium using a first liquid A for forming the image containing apolymerizable or crosslinkable material, and a second liquid B having adifferent composition from the composition of the first liquid A, themethod comprising: applying the second liquid B onto the same area atwhich the image is to be formed by the first liquid A or a wider areathan the area at which the image is to be formed by the first liquid A,of the recording medium which is impermeable or slowly-permeable; andjetting the first liquid A onto the recording medium where the secondliquid B has been applied so that at least a droplet a1 and a droplet a2of the first liquid A have an overlap portion, wherein the liquid B hasa solubility parameter value of 35 or less and the difference of thesolubility parameter value of the liquid B and the solubility parametervalue of the liquid A is 10 or less; wherein the liquid B contains alipophilic solvent in an amount of 50% by mass or more based on thetotal mass of the liquid B, said lipophilic solvent being an organicsolvent having a boiling point higher than 100° C.; and wherein theliquid A and liquid B each have a viscosity at 25° C. in the range of 5to 100 mPa·s.
 2. The ink jet recording method according to claim 1,wherein the solubility parameter value of the second liquid B is 30 orless.
 3. The ink jet recording method according to claim 1, wherein anoverlap ratio at the overlap portion is in the range of 10% to 90%. 4.The ink jet recording method according to claim 1, wherein the secondliquid B farther contains a polymerization initiator.
 5. The ink jetrecording method according to claim 1, wherein the first liquid Afurther contains a colorant.
 6. The ink jet recording method accordingto claim 1, wherein a time interval between the finishing point of theapplication of the second liquid B and the staffing point of the jettingof the droplet a1 is in the range of 5 μ seconds to 400 m seconds. 7.The ink jet recording method according to claim 1, wherein the averagevolume of the droplet a1 and droplet a2 of the first liquid A is 0.1picoliter to 100 picoliters.
 8. The ink jet recording method accordingto claim 1, wherein the polymerizable material is polymerized or thecrosslinkable material is crosslinked by applying activation energyafter jetting the droplets of the first liquid A.
 9. The ink jetrecording method according to claim 1, wherein the solubility parametervalue of the second liquid B is 25 or less.
 10. The ink jet recordingmethod according to claim 1, wherein the difference between thesolubility parameter value of the first liquid A and the solubilityparameter value of the second liquid B is 5 or less.
 11. The ink jetrecording method according to claim 3, wherein the overlap ratio at theoverlap portion is 30% to 70%.
 12. The ink jet recording methodaccording to claim 8, wherein the activation energy is applied byirradiation of ultraviolet rays.
 13. The ink jet recording methodaccording to claim 1, wherein the content of the lipophilic solvent is50% by mass to 100% by mass based on the total mass of the liquid B. 14.The ink jet recording method according to claim 4, wherein the secondliquid B contains the polymerization initiator so that the content ofthe polymerization initiator is in the range of 0.5 to 20% by mass basedon the amount of the polymerizable or crosslinkable material per unitarea.
 15. The ink jet recording method according to claim 1, wherein themass ratio of the second liquid B applied per droplet of the droplets a1and a2 is in the range of 0.05 to 5 based on the mass of one droplet ofthe droplets a1 and a2.
 16. The ink jet recording method according toclaim 1, wherein the mass ratio of the second liquid B applied perdroplet of the droplets a1 and a2 is in the range of 0.1 to 1 based onthe mass of one droplet of the droplets a1 and a2.
 17. The ink jetrecording method according to claim 1, wherein the content of thepolymerizable or crosslinkable material in the first liquid A is in therange of 50 to 99.6% by mass based on the mass of the total solids inthe first liquid A.
 18. The ink jet recording method according to claim1, wherein the content of the polymerizable or crosslinikable materialin the first liquid A is in the range of 80 to 99.0% by mass based onthe mass of the total solids in the first liquid A.